Optical form measurement system using a line-scan interferometer and distance measuring interferometers for run-out compensation of the rotational object stage

摘要

Positioning an interferometric sensor with respect to the specimen requires a precise and expensive motion system toretain the sensors accuracy. A cost-efficient and precise setup requires a compensation of any run-out that the motionsystem induces. This contribution demonstrates that run-outs of a rotational axis can be compensated by implementing alow-cost interferometric point sensor to a previously presented interferometric line-scan system. Furthermore, the setupis extended by an evaluating algorithm that is capable of evaluating the line-sensor’s measurement data in real-time,using either a CPU or a GPU. An improved mechanical design of the interferometric sensor is introduced. It consists offewer mechanical parts compared to previous versions, thus making the sensor more efficient in production and morerobust against vibrations. An up-to-date high-speed line camera with a length of 4,000 pixels and line rate of up to 200kHz increases the measurement rate of the sensor to up to 2,000 height values per second per camera pixel, enabling thesensor to evaluate 8 million height values per second.